Rice protein

Rice protein is what is left when the starch is taken out of the grain. Rice endosperm is roughly four-fifths starch and under a tenth protein, so the commercial route is not to extract the protein but to destroy the starch around it: broken rice or whole-grain rice is milled into a slurry, alpha-amylase and glucoamylase hydrolyse the starch into soluble sugars, and the insoluble protein fraction is separated, washed and dried at low temperature. US Customs described exactly this process when it ruled on rice protein powder imported from India, describing rice ground and treated with alpha-amylase to separate starch from protein, yielding a fine powder concentrate. No hexane or other organic solvent is involved, which is why the material passes cleanly into organic and clean-label programmes. India mills more rice than any other country, so broken-rice feedstock is a domestic co-product rather than an import line, and that is the structural reason Indian rice protein prices the way it does. The amino acid profile is the thing to plan the formulation around. A published comparison of organic brown rice protein against soy and whey found roughly 77-78% total amino acids by weight in the concentrate and isolate, with branched-chain amino acids at about 18% of total amino acids and essential amino acids at 36-38%. Rice is strong where dairy is weak: methionine plus cysteine run 4.3-5.3% of total amino acids. It is weak where legumes are strong. Lysine sits at only 2.7-3.1% of total amino acids against 6.0% for soy isolate and 9.7% for whey isolate, which makes lysine the limiting amino acid. That is the entire reason the rice-and-pea blend exists as a category: pea protein is lysine-rich and sulphur-amino-acid-poor, rice is the mirror image, and blending the two at roughly 70:30 or 30:70 fills both gaps. Buyers building a single-source vegan protein almost always come back asking for the pea line as well. Handling is straightforward with two caveats. First, rice protein does not dissolve, it disperses. It is largely insoluble at neutral pH and settles out of a still liquid, so it suits shakes, bars and baked goods rather than clear ready-to-drink beverages, and finer meshes are usually specified to soften the chalky mouthfeel. Second, arsenic. Rice takes up inorganic arsenic from paddy soil and water more readily than other cereals, and concentrating the protein does not leave the contaminant behind. No regulatory maximum is written specifically for rice protein, so buyers set a contract limit and reference the rice limits: Codex allows 0.35 mg/kg inorganic arsenic in husked rice, and the EU tightened non-parboiled milled rice to 0.15 mg/kg under Commission Regulation (EU) 2023/465. Ask for speciated ICP-MS data on every lot rather than a total-arsenic figure, because total arsenic tells you nothing useful about compliance.